Ca2+-Induced Changes of Surfactin Conformation: A FTIR and Circular Dichroism Study

Previous NMR studies on surfactin proposed two γ or β-turn-containing conformers while recent CD studies described β-sheets and α-helices in surfactin. Since these data were not obtained in the same conditions, the conformation of surfactin was reinvestigated by FTIR spectroscopy, a diagnostic metho...

Full description

Saved in:
Bibliographic Details
Published in:Biochemical and biophysical research communications 2001-03, Vol.282 (1), p.361-367
Main Authors: Vass, Elemér, Besson, Françoise, Majer, Zsuzsa, Volpon, Laurent, Hollósi, Miklós
Format: Article
Language:English
Subjects:
circular dichroism
conformation
Fourier transform infrared
surfactin
turns
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Previous NMR studies on surfactin proposed two γ or β-turn-containing conformers while recent CD studies described β-sheets and α-helices in surfactin. Since these data were not obtained in the same conditions, the conformation of surfactin was reinvestigated by FTIR spectroscopy, a diagnostic method for β-sheets. In trifluoroethanol, the FTIR spectra of surfactin and its diester are compatible with γ and/or β-turn(s) and the differences in their CD spectra show the importance of the Glu1 and Asp5 COOH groups in stabilizing the lipopeptide conformation. The calcium-induced spectral changes of both lipopeptides suggest a first binding of the divalent ions to the surfactin COOH groups (until calcium-lipopeptide mole ratio reached 1) followed by bulk conformational changes (at higher mole ratios). In Tris buffer at pH 8.5, the FTIR amide I band shape, without the typical 1610–1628 and 1675–1695 cm−1 bands, ascertains the absence of β-sheets.
ISSN:0006-291X
1090-2104
DOI:10.1006/bbrc.2001.4469